APPLICANT'S ABSTRACT: This proposed investigation extends prior research efforts by Edna Foa and Joseph Volpicelli in the evaluation of pharmacological and cognitive-behavioral treatments for alcohol dependence (AD) and post- traumatic stress disorder (PTSD), and capitalizes on their combined expertise in evaluating a comprehensive treatment program developed for patients with comorbid AD and PTSD. The comorbidity of AD and PTSD is a significant public mental health problem because the risk for AD dramatically increases among individuals with trauma history or PTSD and vice versa. The two disorders are thought to form a vicious cycle in which PTSD leads to abuse of alcohol; alcohol abuse impedes recovery from the traumatic experience thus contributing to the maintenance of PTSD; and PTSD in turn further escalates and entrenches alcohol abuse. Although promising treatments for AD and PTSD have been identified, comprehensive programs that address both disorders simultaneously have not been empirically tested. Specifically, the opiate antagonist naltrexone has been well established as an efficacious treatment for AD, but research has not specifically addressed its efficacy in patents with PTSD, who are especially prone to treatment attrition and noncompliance. Similarly, cognitive- behavioral treatment of PTSD by prolonged exposure (PE) is the most validated psychosocial treatment for PTSD; however, its efficacy in patients who abuse alcohol is unknown because AD is typically an exclusion criterion in such research. In the proposed study we will evaluate the efficacy of combining these empirically validated treatments for a group of patients who exhibit comorbid AD and PTSD. The proposed study compares four, 6-month treatment conditions in a 2 (naltrexone vs. placebo) by 2 (PE vs. No PE) research design. The four conditions are: 1) 100mg. naltrexone with PE; 2) naltrexone alone; 3) pill placebo with PE; 4) pill placebo alone. An enhanced medication management intervention will accompany all treatment conditions. PE will be provided by experienced psychologists trained in manual protocols. The study will include 200 patients (50/group) diagnosed with AD and comorbid PTSD. Symptoms will be evaluated before, during, and at the end of treatment, and at 9 and 12 months following study entry. Our primary study objective is to compare the short and long term effects of the combined treatments to those of each treatment in isolation on symptoms of AD and of PTSD. This study offers a model for combining and evaluating interventions in diverse treatment modalities for addressing comorbidity in AD, in a major step toward the development of theoretically driven and empirically validated treatments for difficult to treat populations.